West Nile Virus

What is West Nile virus?

West Nile virus is an emerging and potentially serious illness, which is spread by a type of mosquito called Culex tarsalis. Most people bitten by an infected mosquito do not become ill. Of those that do become ill, most develop mild symptoms such as fever, headache, fatigue and body aches. Less frequently, West Nile virus may cause more serious illness (West Nile Neurological Syndrome), including encephalitis, an inflammation of the brain.


What should I do if I think I have West Nile virus?

Anyone experiencing severe symptoms such as persistent high fever, muscle weakness, and headache should seek medical attention immediately. For specific advice regarding medical care, contact your health care provider, or Health Links-Info Sante at 788-8200 in Winnipeg or toll-free at 1-888-315-9257.

What can I do to prevent West Nile virus infection?

Avoid mosquito bites

  • Minimize the time you spend outdoors between dusk and dawn when Culex mosquito activity is highest.
  • Wear light-coloured, loose-fitting, long-sleeved tops and long pants.
  • Apply insect repellent, except on infants (refer to the link below which contains guidelines for appropriate use and application of insect repellents).

    - "What You Need to Know About Insect Repellent"

  • Cover baby carriages and strollers with fine mesh netting to protect infants.
  • Ensure all doors and windows fit properly and are equipped with tight fitting, fine mesh screen.


Reduce mosquito numbers

Culex mosquitoes breed in or around small amounts of standing water and water-filled containers. Reduce mosquito numbers by doing the following:

  • Drain standing water from eavestroughs and other items that might collect water, such as old tires and children’s toys.
  • Empty and clean bird baths weekly.
  • Ensure that openings in rain barrels are covered with mosquito screening or tightly sealed.
  • Cut grass and trim hedges around your home.



What is the Winnipeg Regional Health Authority doing about West Nile virus?

The Winnipeg Regional Health Authority is working with the City of Winnipeg, Regional Municipalities of East and West St. Paul, the Province of Manitoba and the Public Health Agency of Canada to prevent West Nile virus infection. Activities include:

  • Active surveillance among birds, mosquitoes and humans to detect the presence of West Nile virus in Winnipeg and Manitoba. For more information, refer to the following links:

    - Manitoba Health

    - Public Health Agency of Canada

  • Mosquito prevention and control programs. For more information refer to the following link:

    - City of Winnipeg Insect Control Branch


  • Communication with the public, media and health care professionals.
  • Public health investigation of West Nile virus cases.


West Nile Virus: General Information

Experts believe that West Nile virus has established itself as a seasonal epidemic in North America, beginning in the summer and continuing into the fall. In Manitoba, human cases were first detected in the summer of 2003.

How does it spread?

Most often, West Nile virus is spread by the bite of an infected mosquito. Mosquitoes are West Nile virus carriers that become infected when they feed on infected birds. Infected mosquitoes can then spread West Nile virus to humans when they bite. For more information, click here.

What are the symptoms?

Most people bitten by an infected mosquito do not become ill. Of those that do, most develop mild symptoms such as fever, headache, fatigue and body aches. Less frequently, West Nile virus may cause more serious illness (West Nile Neurological Syndrome), including encephalitis, an inflammation of the brain. Encephalitis may lead to serious complications, such as weakness, paralysis, confusion and death. People with existing medical conditions and older adults are more at risk for serious illness, although, illness has occurred in all age groups.



How soon do infected people get sick?

Usually, people develop symptoms between 3 and 14 days after being bitten by an infected mosquito.

How is it treated?

There is no vaccine or specific treatment for West Nile virus. Milder symptoms of West Nile virus usually improve without medical care. In more severe cases, people are typically hospitalized and receive support treatment including intravenous fluids, help with breathing and nursing care.

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